Answer:
look at my explanation.
Explanation:
What is an Expression?
An expression is a sentence with a minimum of two numbers and at least one math operation. This math operation can be addition, subtraction, multiplication, and division. The structure of an expression is:
 Expression = (Number, Math Operator, Number)
For example, 
 = 7 + 9 
 = 23 × 4
 = 37 – 6 
 = 25 + 9 – 4 ÷ 2